1. Field of the Invention
The present invention relates to a LCD projection system and, more particularly, to such a LCD projection system that uses three LCOS (liquid crystal on silicon) for image projection output.
2. Description of the Related Art
Due to the limitation of CRT dimensions and for the sake of manufacturing cost, it is difficult to make a big scale CRT monitor. Nowadays, LCD projection technology has been well developed. Various LCD projection systems of small size and weight have been made, and have appeared on the market. Regular LCD projection systems include two types, one having one single LCOS (liquid crystal on silicon) and the other having three LCOS. A LCD projection system with three LCOS has high resolution and high brightness, however its manufacturing cost is high. Currently, most LCD projection systems are based on penetrative projection type projection system has the drawback of a low aperture ratio.
The present invention has been accomplished under the circumstances in view. It is therefore the main object of the present invention to provide a LCD projection system, which has a high aperture ratio. It is another object of the present invention to provide a LCD projection system, which has a compact size. It is sill another object of the present invention to provide a LCD projection system, which has a simple structure. It is still another object of the present invention to provide a LCD projection system, which is inexpensive to manufacture. To achieve these and other objects of the present invention, the LCD projection system comprises a beam splitter adapted to split a polarized light beam of three primary colors passing from a non-polarized white light through a polarized component of the LCD projection system into a light of two primary colors and a light of one primary color; a first polarization element disposed in the light output side of the beam splitter and adapted to polarize the light of two primary colors; a second polarization element disposed in the light output side of the beam splitter and adapted to polarize the light of one primary color; a dichroic element provided near one side of the first polarization element and adapted to separate the two colors of the light of two primary colors; modulator means disposed at one side relative to the second polarization element and the dichroic element and adapted to modulate the light of tow primary colors and the light of one primary color and to reflect modulated light for output; a retarder provided between the first polarization element and the polarization element; and a projection lens disposed near one side of the first polarization element and adapted to project modularized light from the modulator means and the first polarization element onto a display screen.